add canonicalizeTimezone conversions

Co-authored-by: Om Mishra <contact@om-mishra.com>

src/components/hooks/useTimezone.ts

@@ -1,5 +1,5 @@
 import { setItem } from '@/lib/storage';
-import { TIMEZONE_CONFIG } from '@/lib/constants';
+import { TIMEZONE_CONFIG, TIMEZONE_LEGACY } from '@/lib/constants';
 import { formatInTimeZone, zonedTimeToUtc, utcToZonedTime } from 'date-fns-tz';
 import { useApp, setTimezone } from '@/store/app';
 import { useLocale } from './useLocale';
@@ -34,5 +34,16 @@ export function useTimezone() {
     return utcToZonedTime(date, timezone);
   };
 
-  return { timezone, saveTimezone, formatTimezoneDate, toUtc, fromUtc };
+  const canonicalizeTimezone = (timezone: string): string => {
+    return TIMEZONE_LEGACY[timezone] ?? timezone;
+  };
+
+  return {
+    timezone,
+    saveTimezone,
+    formatTimezoneDate,
+    toUtc,
+    fromUtc,
+    canonicalizeTimezone,
+  };
 }